Tai Chi and Cardiovascular Health
There is evidence, though sometimes controversial, that exercise improves many aspects of cardiovascular health including reduced incidence of coronary heart disease, stroke, and hypertension. , ,  The majority of this research has focused on the impact of vigorous or moderate exercise. Less is known about the cardiovascular benefits of lower intensity exercise, such as Tai Chi.
A growing body of evidence suggests Tai Chi practice, even over short periods of time, may improve cardiovascular health. Depending on how it is practiced, Tai Chi has been characterized as a low to moderate intensity exercise. Three studies are briefly discussed to illustrate the types of evidence available to evaluate the impact that Tai Chi may have on components of cardiovascular health. Young et al.  conducted a well designed, randomized controlled trial with 62 subjects that compared the effects of aerobic exercise versus Tai Chi on blood pressure in mildly hypertensive older adults. Over the 12-week study period, Tai Chi was observed to be equally effective as aerobic exercise in reducing both systolic and diastolic blood pressure. Lai et al.  conducted a longitudinal, prospective study comparing two-year trends in cardiorespiratory function of a group of elderly Tai Chi practitioners (n=45) with an age-matched, sedentary control group (n=39). Their results suggest that Tai Chi may delay the decrease in aerobic capacity usually found with aging. Lan et. al.  conducted a cross-sectional, case-controlled study to evaluate the health benefits of long-term, geriatric Tai Chi practitioners. Cycle ergometry revealed that peak oxygen uptake was greater for Tai Chi practitioners (n=41) compared to age-matched sedentary subjects (n=35). No adverse effects related to the short- or long-term practice of Tai Chi were reported in any of these studies. These and other studies are summarized in reviews by Li et al.  and Lan et al. .
In summary, these and related studies suggest that Tai Chi is a safe exercise, even for frail elders, and may be beneficial to various aspects of cardiovascular health. It requires no specialized equipment, is relatively inexpensive and can be taught/learned in a group setting. Tai Chi appears to elicit a cardiovascular response equivalent to that associated with moderate intensity exercise, and as such meets the American College of Sports Medicine, American Heart Association, and Centers for Disease Control recommendations for daily performance of low- to moderate-intensity activities . However, studies have yet to investigate whether the physiological mechanisms by which Tai Chi impacts cardiovascular health are the same as those believed to relate to more typical endurance and aerobic training .